The invention relates to a noise reduction circuit for stereo signals comprising a control input terminal, first and second outputs as well as a controllable coupling circuit for a controllable mutual signal coupling between the two outputs.
Such a noise reduction circuit is disclosed in German patent application No. 24, 10 430, which has been laid open to public inspection. The noise which may be audible when reproducing stereophonic sound signals can be reduced by changing over to a more or less monophonic reproduction. In the known noise reduction circuit this procedure is used for reducing the noise impression during soft sound passages wherein the amplitude of the sound signal is below a certain preset fixed threshold value. The signal coupling between the two outputs is then maximal. During loud sound passages wherein the amplitude of the sound signal exceeds said threshold value the two outputs are decoupled from one another, which results in a stereophonic reproduction. So with the prior art noise reduction circuit the spatial stereo effect disappears during the soft sound passages, whereas the noise may disturb the stero reproduction in an annoying manner during the loud sound passages.